The present invention relates to a starting and driving unit for an internal combustion engine of a motor vehicle.
Such driving units are well known, and one of them is disclosed for example in the German patent document DE 30 48 972 C2.
New driving concepts which are optimized in particular with respect to environmental protection and fuel consumption are preferably designed so that the internal combustion engine is turned off when the vehicle is stopped, for example at a traffic light or during operational phases in which no drive moment is transmitted from the internal combustion engine. Such an operational procedure can be performed by a START-STOP automatic operation (SSA) and INERTIA-USE automatic operation (IUA). In the vehicles with SSA the number of starts is increased relative to conventional vehicles from 30,000 to 200,000 and in the vehicles with IUA it is increased to more than 400,000. Mass-minimized conventional starters are equipped by special features for an SSA operation. The problem however resides in the open, non-lubricated transmission with a starter pinion and the toothed rim in which the pinion must be engaged during the start. For high starting numbers such a solution is no longer suitable. An aide to this is an oil-lubricated toothed rim.
In the above mentioned prior art, a pulse-starting device is proposed which has low wear and noise. The required starting energy is stored in an inertia-wheel which is freely rotatable on the crank shaft. For starting the internal combustion engine, the motor is accelerated to a sufficiently high rotary speed by closing the motor-side coupling.
For first starts at extremely low temperatures there are however not acceptable long winding-up times for the inertia-wheel. For subsequent starts in warm internal combustion engines, for example at a traffic light or at an end of a pushing phase also not acceptable winding-up times occur when a running-out of the inertia-wheel was allowed to the point of stoppage.
The same problem occurs in the device disclosed in the German patent document DE 29 17 139 A1. In this known driving unit an inertia mass of the crank shaft is turnable on and off, and the internal combustion engine during deceleration, during breaking or during pushing operation can run further by interruption of the drive train with a minimum rotary speed, for example the idle running rotary speed. During short-time stops, for example traffic light stops or the like, the drive train however is interrupted, the internal combustion engine is stopped, while the inertia mass is further rotated and then during subsequent starts of the internal combustion engine, it is again coupled through the coupling. It is therefore possible in the case of considerably dropped rotary speed of the inertia mass to use an electric motor in order to maintain the rotary speed of the inertia mass at a predetermined rotary speed level.
Generally with the use of a classic starter or a pulse start via a switchable inertia-wheel, the requirements for subsequent starts with respect to starting time, low noise, wear, service life, and electrical capacity for the high number of 400,000 starting cycles are satisfied only partially.